Sunspots appear dark due to their cooler temperatures relative to the sun’s surface. Despite being cooler, they maintain a scorching heat of 4,000 °K, contrasted with the sun’s overall temperature of 5,778 °K.
Heat a metal rod slightly and the spot burns bright. Heat another part even hotter, and it burns even brighter, making the first spot look darker. Sunspots work similarly. The higher temperature around a sunspot makes it look darker than it really is.
Why Do Sunspots Appear?
Sunspots form when the sun’s convective flow interacts with concentrated magnetic fluxes by the photosphere. These fluxes create pressure, cooling the gases and expanding them outward into the corona.
The sun’s convective flow, driven by heat from its core, produces energy. The sun also generates a magnetic field. Together, these elements create sunspots.
Sunspots generally appear in pairs and last from a few days to weeks. As they move across the sun’s surface, they might disappear and reappear in new locations. Their activity cycles over 11 years, peaking with more frequent occurrences.
The 11-Year Cycle
The 11-year cycle is an observed pattern of the sun, first identified by astronomer Heinrich Schwabe, who noticed sunspot activity fluctuated between peak and low phases.
The cause of the 11-year cycle isn’t fully understood, but it’s believed to be connected to the sun’s magnetic field.
Sunspots and Correlation to Earth
The sunspot cycle impacts Earth’s climate. Scientists are still trying to understand this connection.
In the 17th century, the sun experienced a period of inactivity, leading to the “Little Ice Age.” During this time, rivers that usually don’t freeze did, and snow became frequent.